Thermoelectric generation is power generation using the Seebeck effect that electromotive force is generated when a temperature difference is provided to both ends of a material. Since a thermoelectric generator using the Seebeck effect does not include a dynamic component and directly converts heat into electricity within a material without separately requiring a fuel, it has very high stability and does not exhaust an environment pollution material. Meanwhile, in order to recover energy discharged as heat during an operation of an internal combustion engine, the thermoelectric generation has been used.
However, when the thermoelectric generator is mounted in the internal combustion engine, heat of the internal combustion engine is absorbed by the thermoelectric generator to lower a temperature of exhaust gas exhausted from the internal combustion engine. It has a negative influence on activity of various post-processing apparatuses mounted in an exhaust pipe in order to purify the exhaust gas exhausted from the internal combustion engine. The reason is as follows. The various post-processing apparatuses are activated at a temperature of 500 to 700° C. to oxidize or reduce NOx, SOx, and PM. However, when the thermoelectric generator is operated, a temperature of the exhaust gas is excessively lowered, such that the temperature of the exhaust gas should be further raised as compared with the related art.
In addition, in the thermoelectric generator mounted in the internal combustion engine according to the related art, heat is transferred from the internal combustion engine to the thermoelectric generator through direct conduction or convection of exhaust heat. However, a constant open circuit voltage may not be obtained due to an excessive temperature fluctuation of the internal combustion engine.